This is a sequel to this post, so same specs.Updated since then to 10.13.4 w/ driver 387.10.10.10.30.107.

I can't get past the OS X login screen. After the MVC EFI boot text is done, Monitor 1 shows garbled dots, and monitor 2 shows gray. After a force shutdown, the next attempt shows black at the same point. And almost always, after another force-shutdown, everything boots and logs in fine. Sometimes it takes more fidgeting, like replugging monitors or rebooting w/ OS driver and back to nVidia driver, and then everything runs fine for a few days.At first this happened once every 1-2 weeks, so there wasn't much to troubleshoot. It has gotten progressively worse, to the point that it now happens every day. Also, it started happening not just at login. The whole system hangs, about once a week. Keyboard still works, but the UI freezes.

Console shows many gpuRestart kernel panic reports, almost all of them of this type: